Neonatal Intensive Care Units (NICUs) have greatly improved health outcomes for sick, preterm, and underweight infants. Since the 1970s various health organizations have recommended a regionalized system of care with high-risk infants referred to a limited number of high-level regional care centers. Despite these recommendations, there has been a large increase in the number of mid-level facilities over the past two decades. Previous literature has documented negative impacts of this "deregionalization," namely a sizable shift in the location of high-risk infant deliveries towards mid-level hospitals and up to 100% higher risk adjusted mortality rates for high-risk infants born in mid-level hospitals compared to high-level hospitals. This project seeks to estimate the causal effects of deregionalization on outcomes and treatment patterns for infants across the health distribution. First, previous estimates of the mortality differential between infants born in hospitals with mid-level and high-level NICUs may be biased by patient sorting. Depending on the reasons behind this sorting, previous estimates may understate or overstate this mortality differential. This project overcomes this bias by using instrumental variables to estimate the causal effect of the type of birth hospital on mortality. Exploiting variation in the distance to the nearest hospital of each care level, this project estimates mortality differentials by comparing identical infants who are born in hospitals with different care levels because their mothers experienced different exposure to these care levels. Second, it is impossible to understand the welfare implications of deregionalization without also knowing the effects on low-risk infants. Infants born above the low or very low birth weight cutoffs comprise a very large population, and mothers of these infants are likely to be the group of patients hospitals are attempting to attract by adopting mid-level NICUs. This project will provide the first estimates of the effects of the level of care available at the hospital of birth on mortality and hospital readmission rates for this population. Finally, this project will estimate the effect of being born in a hospital with a mid-level NICU on treatment patterns. Hospitals may have financial incentives to provide excessive treatment, and deregionalization may magnify these incentives. Quantifying the effect of deregionalization on the amount of resources utilized in newborn care and how this utilization interacts with health outcomes is essential to making policy decisions about the organization and efficiency of care. There has been a large increase in the number of hospitals with less sophisticated Neonatal Intensive Care Units over the past two decades. This project seeks to describe how this change has affected the treatment and health outcomes of high- and low-risk infants. Understanding these effects is necessary to fully evaluate the public health consequences of the increased availability of this type of care.